How do I ensure about non negative column?

I need to create a table Branch with columns branch_name and branch_city character type, assets as integer type. branch_name is the primary key and I have to ensure that assets are non negative.

I tried like

CREATE TABLE Branch
(
    branch_name navarchar(100) primary key,
    branch_city nvarchar(100),
    assests int NOT NULL
)

How do I ensure about non negative column?

3 Answers